Outdoor junction boxes for telephone and/or power lines must provide a safe, durable, and weatherproof housing within which multiple wires can be terminated. For safety reasons, such junction boxes are typically mounted well out of reach, such as high overhead on telephone poles or buildings.
The junction boxes house standardized terminal blocks that have multiple wire termination silos spaced along an outwardly facing surface. The silos house contacts which are electrically interconnected within the terminal block. Wires may be inserted into the open silos through apertures or slots of the contacts, and the contacts are then manipulated to penetrate through the wire insulation and electrically engage the conductors of the wires. This way, the appropriate line-to-line connections are completed. It is common for five, twelve, and twenty-five connections (with twice the number of terminations) to be completed in the above-described manner at one junction box.
Of course, the enclosure which houses the terminal block(s) must provide individual access for each line interiorly of the enclosure, and it must permit convenient access for servicing. In addition, the enclosure must be weatherproof, tamper-proof, rugged, and durable.
Conventional junction boxes are standard rectangular enclosures having a swinging front panel hinged along one side that opens outward to provide access for servicing. Multiple apertures are spaced along the bottom or sides of the enclosure to provide separate access for the lines. The terminal block(s) are centrally mounted in the enclosure with sockets facing outward, and the lines are routed into the appropriate sockets.
Specifications for such enclosures are proposed in Bellcore Technical Advisory TA-NWT-000014, Issue 3, November 1990, "Generic Requirements of Aerial Cable Terminals," issued by Bell Communications Research, Inc. Such requirements are directed toward protection of electrical connections between main distribution cables and service lines for long in-service use against all environmental effects commonly encountered, including precipitation, temperature extremes, corrosion, dust, debris, ultraviolet light, insects, rodents, reptiles, birds, and so forth. Also, such enclosures must present no environmental or safety hazards.
Since a ladder is typically required to gain access, conventional terminal enclosure designs are not well-suited for aerial telephone and/or power line applications. With those conventional doors which open forwardly and to the side, it is inherently awkward for a maintenance person to open the door panel while standing on a ladder in front of the enclosure. There is usually insufficient clearance to allow full opening of the door, and the maintenance person is incapable of backing up. This problem often prompts the maintenance person to compromise his/her safety by leaning back on the ladder. Even if the maintenance person manages to open the door panel, there is usually a continuing struggle to keep it open. The wind and/or gravity often forces the door panel closed, and this is most awkward since both hands are invariably needed for working on the terminal block. If the doors are of the type that are lowered vertically during opening, the lower edge of the door commonly interferes with the ladder. The door may not lower fully, or it may snag on the ladder, thereby obstructing raising of the door for closure. It would not be desirable for a door to open vertically in a guillotine manner unless its stability in the open position is guaranteed. Otherwise, the safety of the service person would be endangered.
Clearly, it would be greatly advantageous to provide a terminal enclosure which can be easily opened with a minimum of frontal clearance and which will remain open for the duration of servicing.